Cellular wireless data access systems typically consist of a set of base stations each with a certain number of sectors and each sector having a transmitter and a receiver with one or multiple antenna elements. Mobile stations are typically assigned to one or more base stations by wireless connections to one sector of each of these base stations. Base stations and sectors are related to geographical areas where the distance to the antennas belonging to the sectors is low, the angular range supported by the antenna corresponds to that area and the channel quality between users located in that area and the base station including interference from other mobile stations/base station is sufficient to establish a wireless connection.
However, connections between a base station and mobile stations that are assigned to the same sector of that base station can typically have significantly different channel qualities and very different path losses depending on their distance to the base station, which typically varies from a few meters up to a few kilometers. For example, WiMAX (IEEE 802.16) uses OFDM/OFDMA and each single radio resource (frequency sub-band or time slot) is used in one point-to-point transmission. Multiplexing and multiple access is done using different, at least approximately orthogonal radio resources. However, in addition to the above problems a strong interference may occur to base stations and mobile stations in systems like WiMAX, if mobile stations are located at sector borders or cell borders, especially if such systems operate in multi-cellular deployments with frequency reuse 1.
U.S. Pat. No. 6,510,174 B1 describes a method and apparatus for facilitating setting of link parameters to improve communication qualities between a mobile station and a base station in a radio communication system. Uplink sounding bursts are generated by a mobile station and transmitted to the network infrastructure. The uplink sounding bursts are analyzed to determine channel conditions upon which the uplink sounding bursts are transmitted. Link parameters are selected based on said analysis.
It is therefore an object of the present invention to provide a measurement basis for advanced interference mitigation schemes.
This object and other objects are solved by the features of the independent claims. Preferred embodiments of the invention are described by the features of the dependent claims.